The present invention relates to a semiconductor device and a method of manufacturing same. For example, it is suited for use in a method of manufacturing a semiconductor device having a trench portion.
There is a semiconductor device having an element isolation structure obtained by forming an insulating film in a trench portion made in the surface, which is a main surface, of a semiconductor substrate. There is also a semiconductor device having an element isolation (deep trench isolation: DTI) structure obtained by forming an insulating film in a trench portion having as aspect ratio, that is, a ratio of the depth of the trench portion to the width of the trench portion, as high as more than 1.
Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2011-66067) discloses a method of manufacturing a semiconductor device including a step of forming a trench that surrounds an element in plan view in the main surface of a semiconductor substrate and a step of forming an insulating film on the element and in the trench. According to Patent Document 1, the insulating film is formed so as to cover the upper surface of the element and to form a space in the trench.
Patent Document 2 (US Patent Application Publication No. 2014-0291767) describes that a space is formed in a trench formed In the main surface of a semiconductor substrate at the side of an element. In a manufacturing step of a semiconductor device described in Patent Document 2, the space is formed in the trench by forming an oxide film that covers the upper surface of the semiconductor substrate and the surface of the trench, removing the oxide film on the semiconductor substrate, and then forming, on the semiconductor substrate, an insulating film contiguous to the side wall of the oxide film in the trench.    [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2011-66067    [Patent Document 2] US Patent Application Publication No. 2014-0291767